Prosthetic heart valve with pouch

ABSTRACT

A valve body circumscribes a longitudinal axis and defines a lumen along the axis. Upstream arms are coupled to the valve body, and extend radially outward from the valve body to respective arm-tips. Downstream legs are coupled to the valve body, and extend radially outward from the valve body and toward the plurality of arms. A flexible pouch extends radially outward from the valve body. The arms and the legs narrow the pouch therebetween to form a narrowed portion of the pouch, thereby defining, in an interior space of the pouch: (a) an inner portion, radially inward from the narrowed portion, and in fluid communication with the lumen, and (b) an outer portion, radially outward from the narrowed portion, and in fluid communication with the inner portion via the narrowed portion. Other embodiments are also described.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a Continuation-In-Part of:

-   -   International patent application PCT/IL2018/050725 to Hariton et        al., filed Jul. 4, 2018, and entitled “Prosthetic heart valve,”        which is a Continuation-In-Part of U.S. patent application Ser.        No. 15/956,956 to Iamberger et al., filed Apr. 19, 2018, and        entitled “Prosthetic heart valve;”    -   U.S. patent application Ser. No. 16/135,969 to Hariton et al.,        filed Sep. 19, 2018, and entitled “Prosthetic valve with        inflatable cuff configured for radial extension,” which claims        benefit of U.S. provisional patent application 62/560,384 to        Hariton et al., filed Sep. 19, 2017, and entitled “Prosthetic        valve and methods of use;” and    -   U.S. patent application Ser. No. 16/135,979 to Hariton et al.,        filed Sep. 19, 2018, and entitled “Prosthetic valve with        inflatable cuff configured to fill a volume between atrial and        ventricular tissue anchors,” which claims benefit of U.S.        provisional patent application 62/560,384 to Hariton et al.,        filed Sep. 19, 2017, and entitled “Prosthetic valve and methods        of use.”

All of the above applications are incorporated herein by reference.

FIELD OF THE INVENTION

Some applications of the present invention relate in general to valvereplacement. More specifically, some applications of the presentinvention relate to prosthetic valves for replacement of a cardiacvalve.

BACKGROUND

Ischemic heart disease causes regurgitation of a heart valve by thecombination of ischemic dysfunction of the papillary muscles, and thedilatation of the ventricle that is present in ischemic heart disease,with the subsequent displacement of the papillary muscles and thedilatation of the valve annulus.

Dilation of the annulus of the valve prevents the valve leaflets fromfully coapting when the valve is closed. Regurgitation of blood from theventricle into the atrium results in increased total stroke volume anddecreased cardiac output, and ultimate weakening of the ventriclesecondary to a volume overload and a pressure overload of the atrium.

SUMMARY OF THE INVENTION

For some applications, an implant is provided having a valve body thatdefines a lumen, an upstream support portion, and a plurality of legs.The implant is percutaneously deliverable to a native heart valve in acompressed state, and is expandable at the native valve. The implantcomprises an inner frame and an outer frame. Typically, the upstreamsupport portion is at least partly defined by the inner frame, and thelegs are at least partly defined by the outer frame. The implant issecured at the native valve by sandwiching tissue of the native valvebetween the upstream support portion and the legs. For someapplications, a flexible pouch extends radially outward from the valvebody. For some such applications, the arms and the legs narrow the pouchtherebetween to form a narrowed portion of the pouch, thereby dividingan interior space of the pouch into (a) an inner portion, radiallyinward from the narrowed portion, and in fluid communication with thelumen, and (b) an outer portion, radially outward from the narrowedportion, and in fluid communication with the inner portion via thenarrowed portion.

There is therefore provided, in accordance with an application of thepresent invention, apparatus, including:

a frame assembly that includes:

-   -   a valve body that circumscribes a longitudinal axis and defines        a lumen along the axis;    -   a plurality of upstream arms that are coupled to the valve body        at a first axial level with respect to the longitudinal axis,        each of the arms extending radially outward from the valve body        to a respective arm-tip; and    -   a plurality of downstream legs that are coupled to the valve        body at a second axial level with respect to the longitudinal        axis, and that extend radially outward from the valve body and        toward the plurality of arms;

a plurality of prosthetic leaflets, disposed within the lumen, andarranged to facilitate one-way upstream-to-downstream fluid flow throughthe lumen, the first axial level being upstream of the second axiallevel; and

a flexible pouch that defines an interior space therein, the pouchshaped and coupled to the frame assembly such that:

-   -   the pouch extends radially outward from the valve body, and    -   the arms and the legs narrow the pouch therebetween to form a        narrowed portion of the pouch, so as to define:        -   an inner portion of the interior space, radially inward from            the narrowed portion, and in fluid communication with the            lumen, and        -   an outer portion of the interior space, radially outward            from the narrowed portion, and in fluid communication with            the inner portion via the narrowed portion.

In an application, at the narrowed portion, the legs extend in anupstream direction past the arms.

In an application, the arms are disposed inside the pouch.

In an application, the arms and the legs are arranged such that, at thenarrowed portion, the arms and the legs alternate circumferentially.

In an application, the inner portion of the interior space is in fluidcommunication with the lumen via a plurality of discrete windows definedby the apparatus.

In an application, the apparatus further includes a belt wrapped aroundthe frame assembly downstream of the windows, circumscribing the lumen,each of the windows being bounded, at a downstream edge of the window,by the belt.

In an application, the leaflets are arranged to form a plurality ofcommissures therebetween, and are attached to the frame assembly at thecommissures, and the belt is disposed over the commissures.

In an application:

the pouch has an upstream surface and a downstream surface, and,

at the narrowed portion, each of the legs pushes the downstream surfacetoward the upstream surface.

In an application, at the narrowed portion, each of the legs pushes thedownstream surface into contact with the upstream surface.

In an application, at the narrowed portion, each of the legs forms arespective bulge in the upstream surface by pressing the downstreamsurface against the upstream surface.

In an application, the pouch is stitched to the arms.

In an application, at the narrowed portion, the pouch is stitched to thearms but not to the legs.

In an application, the frame assembly includes (i) a valve frame thatdefines the valve body and the plurality of upstream arms, and (ii) anouter frame that circumscribes the valve frame, and defines theplurality of downstream legs.

In an application, an upstream portion of the pouch is attached to thevalve frame, and a downstream portion of the pouch is attached to theouter frame.

In an application, the apparatus further includes at least onecoagulation component, disposed within the outer portion of the interiorspace, and configured to promote blood coagulation within the outerportion of the interior space.

In an application, the coagulation component is annular, and, within theouter portion of the interior space, circumscribes the longitudinalaxis.

There is further provided, in accordance with an application of thepresent invention, apparatus, including:

a frame assembly that includes:

-   -   a valve body that circumscribes a longitudinal axis and defines        a lumen along the axis;    -   a plurality of upstream arms that are coupled to the valve body        at a first axial level with respect to the longitudinal axis,        each of the arms extending radially outward from the valve body        to a respective arm-tip; and

a plurality of downstream legs that are coupled to the valve body at asecond axial level with respect to the longitudinal axis, and thatextend radially outward from the valve body and toward the plurality ofarms;

a tubular liner that lines the lumen, and that has an upstream end and adownstream end;

a plurality of prosthetic leaflets, disposed within the lumen, attachedto the liner, and arranged to facilitate one-way upstream-to-downstreamfluid flow through the lumen, the first axial level being upstream ofthe second axial level;

a first sheet of flexible material, the first sheet having (i) a greaterperimeter, and (ii) a smaller perimeter that defines an opening, thefirst sheet being attached to the plurality of arms with the openingaligned with the lumen of the valve body; and

a second sheet of flexible material:

-   -   the second sheet having a first perimeter and a second        perimeter,    -   the first perimeter being attached to the greater perimeter of        the first sheet around the greater perimeter of the first sheet,    -   the second sheet extending from the first perimeter radially        inwards and downstream toward the second perimeter, the second        perimeter circumscribing, and attached to, the valve body at a        third axial level that is downstream of the first axial level,        and:

the first sheet, the second sheet, and the liner define an inflatablepouch therebetween, the inflatable pouch defining an interior spacetherein, the first sheet defining an upstream wall of the pouch, thesecond sheet defining a radially-outer wall of the pouch, and the linerdefining a radially-inner wall of the pouch, and

each of the legs presses the second sheet into contact with the firstsheet.

In an application, the arms are disposed inside the pouch.

In an application, each of the legs forms a respective bulge in thefirst sheet by pressing the second sheet against the first sheet.

In an application, the legs extend in an upstream direction past thearms.

In an application, the frame assembly includes (i) a valve frame thatdefines the valve body and the plurality of upstream arms, and (ii) anouter frame that circumscribes the valve frame, and defines theplurality of downstream legs.

In an application, an upstream portion of the pouch is attached to thevalve frame, and a downstream portion of the pouch is attached to theouter frame.

In an application, the plurality of legs forms a narrowed portion of thepouch by pressing the second sheet into contact with the first sheet,the narrowed portion of the pouch circumscribing the valve body.

In an application, at the narrowed portion, the second sheet is notstitched to the legs.

In an application, the arms and the legs are arranged such that, at thenarrowed portion, the arms and the legs alternate circumferentially.

In an application, the narrowed portion of the pouch shapes the pouch todefine:

-   -   an inner portion of the interior space, radially inward from the        narrowed portion, and in fluid communication with the lumen, and    -   an outer portion of the interior space, radially outward from        the narrowed portion, and in fluid communication with the inner        portion via the narrowed portion.

In an application, the apparatus further includes at least onecoagulation component, disposed within the outer portion of the interiorspace, and configured to promote blood coagulation within the outerportion of the interior space.

In an application, the coagulation component is annular, and, within theouter portion of the interior space, circumscribes the longitudinalaxis.

In an application, the interior space is in fluid communication with thelumen via a plurality of discrete windows defined by the apparatus.

In an application, the apparatus further includes a belt wrapped aroundthe frame assembly downstream of the windows, circumscribing the lumen,each of the windows being bounded, at a downstream edge of the window,by the belt.

In an application, the leaflets are arranged to form a plurality ofcommissures therebetween, and are attached to the frame assembly at thecommissures, and the belt is disposed over the commissures.

The present invention will be more fully understood from the followingdetailed description of applications thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-E and 2 are schematic illustrations of an implant and a frameassembly of the implant, in accordance with some applications of theinvention;

FIGS. 3A-F are schematic illustrations showing the implantation of theimplant at a native valve of a heart of a subject, in accordance withsome applications of the invention;

FIGS. 4, 5A-C, and 6 are schematic illustration of implants and theirframes, in accordance with some applications of the invention;

FIG. 7 is a schematic illustration of an outer frame of a frame assemblyof an implant, in accordance with some applications of the invention;

FIG. 8 is a schematic illustration of a frame assembly, in accordancewith some applications of the invention;

FIGS. 9A-B are schematic illustrations of an inner frame, and an implantcomprising the inner frame, in accordance with some applications of theinvention;

FIGS. 10A-B are schematic illustrations of an inner frame, and animplant comprising the inner frame, in accordance with some applicationsof the invention;

FIGS. 11A-B are schematic illustrations of an inner frame, and animplant comprising the inner frame, in accordance with some applicationsof the invention;

FIGS. 12A-H are schematic illustrations of a technique for use with aframe of a prosthetic valve, in accordance with some applications of theinvention;

FIGS. 13A-E, 14A-D, 15A-C, 16A-C, 17, 18A-C, and 19 are schematicillustrations of an implant, and steps in the assembly of the implant,in accordance with some applications of the invention; and

FIGS. 20, and 21A-C are schematic illustrations of an implant, inaccordance with some applications of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is made to FIGS. 1A-E and 2, which are schematic illustrationsof an implant 20 and a frame assembly 22 of the implant, in accordancewith some applications of the invention. Implant 20 serves as aprosthetic valve for use at a native heart valve of a subject—typicallythe mitral valve. Implant 20 has a compressed state forminimally-invasive (typically transluminal, e.g., transfemoral)delivery, and an expanded state into which the implant is transitionedat the native heart valve, and in which the implant provides prostheticvalve functionality. Implant 20 comprises frame assembly 22, flexiblesheeting 23, and a valve member such as prosthetic leaflets 58.

FIGS. 1A-E show implant 20 and frame assembly 22 in the expanded state.For clarity, FIGS. 1A-D show frame assembly 22 alone. FIG. 1A shows anisometric exploded view of frame assembly 22, and FIG. 1B shows a sideexploded view of the frame assembly. FIGS. 1C and 1D are side- andtop-views, respectively, of frame assembly 22, assembled. FIG. 1E is aperspective view of implant 20, including sheeting 23 and leaflets 58.

Implant 20 has an upstream end 24, a downstream end 26, and defines acentral longitudinal axis ax1 therebetween. Frame assembly 22 comprisesa valve frame 30 that comprises a valve body (which is a generallytubular portion) 32 that has an upstream end 34 and a downstream end 36,and is shaped to define a lumen 38 through the valve body from itsupstream end to its downstream end. Valve body 32 circumscribes axisax1, and thereby defines lumen 38 along the axis. Throughout thisapplication, including the specification and the claims, unless statedotherwise, “upstream” and “downstream,” e.g., with respect to the endsof implant 20, are defined with respect to the longitudinal axis ofimplant 20, by the orientation and functioning of leaflets 58, whichfacilitate one-way upstream-to-downstream fluid flow through lumen 38.

Valve frame 30 further comprises a plurality of arms 46, each of which,in the expanded state, extends radially outward from valve body 32. Inthis context, the term “extends radially outward” is not limited toextending in a straight line that is orthogonal to axis ax1, but rather,and as shown for arms 46, includes extending away from axis ax1 whilecurving in an upstream and/or downstream direction. Typically, and asshown, each arm 46 extends from valve body 32 in an upstream direction,and curves radially outward. That is, the portion of arm 46 closest tovalve body 32 extends primarily upstream away from the valve body (e.g.,extending radially outward only a little, extending not at all radiallyoutward, or even extending radially inward a little), and the arm thencurves to extend radially outward. The curvature of arms 46 is describedin more detail hereinbelow.

Valve body 32 is defined by a repeating pattern of cells that extendsaround central longitudinal axis ax1. In the expanded state of eachtubular portion, these cells are typically narrower at their upstreamand downstream extremities than midway between these extremities. Forexample, and as shown, the cells may be roughly diamond or astroid inshape. Typically, and as shown, valve body 32 is defined by two stacked,tessellated rows of cells—an upstream row 29 a of first-row cells, and adownstream row 29 b of second-row cells. Frame 30 is typically made bycutting (e.g., laser-cutting) its basic (i.e., raw) structure from atube of, for example, Nitinol (followed by re-shaping and heat treatingto form its shape-set structure). Although valve body 32 is thereforetypically monolithic, because the resulting cellular structure of valvebody 32 resembles an open lattice, it may be useful to describe it asdefining a plurality of joists 28 that connect at nodes 100 to form thecellular structure.

Typically, and as shown, each arm 46 is attached to and extends from asite 35 that is at the connection between two adjacent cells of upstreamrow 29 a. That is, site 35 is a connection node between first-row cells.The tessellation between rows 29 a and 29 b is such that site 35 mayalternatively be described as the upstream extremity of cells ofdownstream row 29 b. That is, the upstream extremity of each second-rowcell is coincident with a respective connection node between first-rowcells. Site 35 is therefore a node 100 that connects four joists 28.Upstream end 34 of valve body 32 may be described as definingalternating peaks and troughs, and sites 35 are downstream of the peaks(e.g., at the troughs).

It is hypothesized by the inventors that connecting arm 46 to valve body32 at site 35 (instead of at upstream end 34) maintains the length ofthe lumen of the tubular portion, but also advantageously reduces thedistance that the tubular portion extends into the ventricle of thesubject, and thereby reduces a likelihood of inhibiting blood flow outof the ventricle through the left ventricular outflow tract. It isfurther hypothesized by the inventors that because each site 35 is anode 100 that connects four joists (whereas each node 100 that is atupstream end 34 connects only two joists), sites 35 are more rigid, andtherefore connecting arms 46 to valve body 32 at sites 35 providesgreater rigidity to each arm.

Sheeting 23 may comprise one or more individual sheets, which may or maynot be connected to each other. The individual sheets may comprise thesame or different materials. Typically, sheeting 23 comprises a fabric,e.g., comprising a polyester, such as polyethylene terephthalate. Arms46 are typically covered with sheeting 23. Typically, and as shown inFIG. 1E, an annular sheet 25 of sheeting 23 is disposed over arms 46,extending between the arms, e.g., so as to reduce a likelihood ofparavalvular leakage. For some such applications, excess sheeting 23 isprovided between arms 46, so as to facilitate movement of arms 46independently of each other. Annular sheet 25 typically covers theupstream side of arms 46, but may alternatively or additionally coverthe downstream side of the arms.

Alternatively, each arm 46 may be individually covered in a sleeve ofsheeting 23, thereby facilitating independent movement of the arms.

Arms 46, and typically the sheeting that covers the arms, define anupstream support portion 40 of implant 20.

Other surfaces of frame assembly 22 may also be covered with sheeting23. Typically, sheeting 23 covers at least part of valve body 32, e.g.,defining a liner 27 that lines an inner surface of the valve body, andthereby defining lumen 38.

Support 40 has an upstream surface, and a downstream surface. Each arm46 is typically curved such that a downstream surface of support 40defines an annular concave region 152, and an annular convex region 154radially outward from the concave region. That is, in region 152 thedownstream surface of support 40 (e.g., the downstream surface of eacharm 46 thereof) is concave, and in region 154 the downstream surface ofthe support is convex.

Concave region 152 extends radially between a concave-region innerradius r1 and a concave-region outer radius r2. Convex region 154extends radially between a convex-region inner radius r3 and aconcave-region outer radius r4. It is to be noted that in this context(including the specification and the claims), the term “radius” means aradial distance from axis ax1.

For some applications, and as shown, each arm 46 has a serpentine shape,such that there is no discernable gap between concave region 152 andconvex region 154. For such applications, each arm 46 has an inflectionpoint where region 152 transitions into region 154. For suchapplications, radius r2 and radius r3 are coincident, and collectivelydefine an inflection radius at which the inflection point of each armlies.

For some applications, radius r1 is the radius of tubular portion 32.For some applications, there is a discernable gap between regions 152and 154. For example, each arm may be curved in regions 152 and 154, buthave a straight portion between these regions.

Although regions 152 and 154 may be locally defined with respect to oneor more particular arms 46, these regions typically completelycircumscribe axis ax1.

Frame assembly 22 further comprises a plurality of legs 50, each ofwhich, in the expanded state, extends radially outward and in anupstream direction from a respective leg-base 66 to a respective leg-tip68. Each leg 50 defines a tissue-engaging flange 54, which is typicallythe most radially outward part of the leg, and includes leg-tip 68.Typically, legs 50 are defined by an outer frame (or “leg frame”) 60that circumscribes and is coupled to valve frame 30.

Frames 30 and 60 define respective coupling elements 31 and 61, whichare fixed with respect to each other at coupling points 52. For someapplications, frames 30 and 60 are attached to each other only atcoupling points 52. Although frames 30 and 60 are attached to each otherat coupling points 52, radial forces may provide further couplingbetween the frames, e.g., frame 30 pressing radially outward againstframe 60.

Typically, coupling points 52 are circumferentially aligned with legs 50(and flanges 54 thereof), but circumferentially offset with respect toarms 46. That is, the coupling points are typically at the samerotational position around axis ax1 as the legs, but are rotationallystaggered with respect to the rotational position of the arms.

Coupling points 52 are typically disposed circumferentially around frameassembly 22 on a transverse plane that is orthogonal to axis ax1. Thatis, coupling points 52 are typically all disposed at the samelongitudinal position along axis ax1. Typically, coupling points 52 aredisposed longitudinally between upstream end 24 and downstream end 26 offrame assembly 22, but not at either of these ends. Further typically,coupling points 52 are disposed longitudinally between upstream end 34and downstream end 36 of tubular portion 32, but not at either of theseends. As shown, tubular portion 32 is typically barrel-shaped—i.e.,slightly wider in the middle than at either end. For some applications,and as shown, coupling points 52 are disposed slightly downstream of thewidest part of tubular portion 32. For example, coupling points 52 maybe 0.5-3 mm downstream of the widest part of tubular portion 32.Alternatively or additionally, the longitudinal distance between thewidest part of tubular portion 32 and coupling points 52 may be 20-50percent (e.g., 20-40 percent) of the longitudinal distance between thewidest part of the tubular portion and downstream end 36.

Coupling elements 31 are typically defined by (or at least directlyattached to) legs 50. Therefore legs 50 are fixedly attached to frame 30at coupling points 52. Despite the fixed attachment of legs 50 to frame30, frame 60 comprises a plurality of struts 70 that extend between, andconnect, adjacent legs. Struts 70 are typically arranged in one or morerings 72, e.g., a first (e.g., upstream) ring 74 and a second (e.g.,downstream) ring 76. For some applications, and as shown, frame 60comprises exactly two rings 72. Each ring is defined by a pattern ofalternating peaks 64 and troughs 62, the peaks being further upstreamthan the troughs. Each ring is typically coupled to legs 50 at troughs62—i.e., such that peaks 64 are disposed circumferentially between thelegs. Peaks 64 are therefore typically circumferentially aligned witharms 46. That is, peaks 64 are typically at the same rotational positionaround axis ax1 as arms 46.

The elongate element of frame 60 that defines leg 50 continues in adownstream direction past ring 74 and coupling element 61, and couplesring 74 to ring 76. However, throughout this patent application, leg 50itself is defined as the free portion of this elongate element thatextends from ring 74. Leg-base 66 may be defined as the region of leg 50that is coupled to the remainder of frame 60 (e.g., to ring 74). Becauseeach leg 50 extends in a generally upstream direction, leg-base 66 mayalso be defined as the most downstream region of leg 50.

In the expanded state, the leg-tip 68 of each leg is typically disposedradially between radius r3 and radius r4. That is, the leg-tip 68 ofeach leg is aligned with convex region 154.

Frame 60 is typically cut from a single tube, e.g., of Nitinol.Therefore, the radial thickness of the frame is typically consistentthroughout—e.g., it is the wall thickness of the tube from which it wascut. However, the circumferential width of components of frame 60 (i.e.,the width of the component measured around the circumference of theframe) may differ. For example, for some applications, a circumferentialthickness W2 of legs 50 may be at least three times greater than acircumferential thickness W1 of struts 70. Greater circumferentialthickness typically provides the component with greater rigidity.

Valve frame 30 and outer frame 60 are typically each cut from respectivemetallic tubes, e.g., of Nitinol. This is typically the case for each ofthe implants described herein. More specifically, for each of theimplants described herein:

-   -   (1) the valve frame is typically cut from a metallic tube to        form a raw valve-frame structure in which the arms and the        projections extend axially from the valve body, and the raw        valve-frame structure is subsequently shape-set to form a        shape-set valve-frame structure in which (i) the valve body is        wider than in the raw valve-frame structure, and (ii) the arms        extend radially outward from the valve body; and    -   (2) the outer frame is typically cut from a metallic tube to        form a raw outer-frame structure in which the legs (including        the flanges) extend axially, and the raw outer-frame structure        is subsequently shape-set to form a shape-set outer-frame        structure in which (i) the rings are wider than in the raw        outer-frame structure, and (ii) the flanges extend radially        outward from the rings.

Prosthetic leaflets 58 are disposed within lumen 38, and are configuredto facilitate one-way liquid flow through the lumen from upstream end 34to downstream end 36. Leaflets 58 thereby define the orientation of theupstream and downstream ends of valve body 32, and of implant 20 ingeneral.

Typically, implant 20 is biased (e.g., shape-set) to assume its expandedstate. For example, frames 30 and 60 may be constructed from ashape-memory metal such as Nitinol or a shape-memory polymer.Transitioning of implant 20 between the respective states is typicallycontrolled by delivery apparatus, such as by constraining the implant ina compressed state within a capsule and/or against a control rod, andselectively releasing portions of the implant to allow them to expand.

FIG. 2 shows implant 20 in its compressed state, for delivery to theheart of the subject, e.g., within a capsule 170 or delivery tube.Capsule 90 may be a capsule or a catheter. For clarity, only frameassembly 22 of implant 20 is shown. In the compressed state, arms 46define a ball 48 at an end of valve body 32. It is to be noted that inthis context, the term “ball” (including the specification and theclaims) means a substantially bulbous element. The ball may besubstantially spherical, spheroid, ovoid, or another bulbous shape.

In the compressed state, frame assembly 22 defines a waist 56 (i.e., iswaisted) at a longitudinal site between the valve body and the ball. Forsome applications, and as shown, waist 56 is longitudinally upstream offrame 60, and is therefore primarily defined by valve frame 30. However,for some such applications, the downstream limit of the waist may bedefined by the upstream limit of frame 60 (e.g., flanges 54 thereof).

It is to be noted that, typically, the bulbous shape of ball 48 isinterrupted at waist 56, i.e., where the frame transitions from the ballto the waist. For some applications, and as shown, valve frame 30 ismonolithic (e.g., cut from a single metal tube), and defines both valvebody 32 and arms 46. For some applications, and as shown, in thecompressed state, the overall shape of valve frame 30 resembles that ofan air rifle pellet or a shuttlecock (e.g., see the cross-section inFIG. 2). For some applications, a longitudinal cross-section of frame 30has an overall shape that resembles a keyhole.

For some applications, at waist 56, frame 30 (and typically frameassembly 22 overall) has a transverse diameter d10 that is less than 5mm (e.g., 2-4 mm). For some applications, ball 48 has a greatesttransverse diameter d11 of 8-12 mm (e.g., 9-11 mm). For someapplications, transverse diameter d10 is less than 40 percent (e.g.,less than 30 percent, such as 10-30 percent) of transverse diameter d11.

Due to waist 56, while implant 20 is in its compressed state anddisposed within capsule 90, the implant and capsule define a toroidalgap 57 therebetween. Toroidal gap 57 circumscribes longitudinal axis ax1of the implant around waist 56. Therefore, valve body 32 extends in afirst longitudinal direction (i.e., in a generally downstream direction)away from gap 57, and arms 46 extend in a second longitudinal direction(i.e., in a generally upstream direction) away from the gap. Forapplications in which implant 20 is delivered to the native valvetransfemorally, valve body 32 is closer to the open end of capsule 90than is gap 57, and arms 46 (e.g., ball 48) are further from the openend of capsule 90 than is gap 57. For some applications, and as shown, adownstream limit of gap 57 is defined by the tips of flanges 54. Forsome applications, and as shown, an upstream limit of gap 57 is definedby the downstream side of arms 46.

It is to be noted that, typically, frame 60 is disposed only downstreamof toroidal gap 57, but the frame 30 is disposed both upstream anddownstream of the toroidal gap.

Reference is again made to FIG. 1E. For some applications, implant 20comprises a polytetrafluoroethylene (e.g., Teflon) ring 78 attached todownstream end 26. Ring 78 circumscribes lumen 38 at downstream end 36of valve body 32, and typically at downstream end 26 of implant 20.Therefore ring 78 serves as a downstream lip of lumen 38. Typically,ring 78 is attached (e.g., stitched) to both frame 30 and frame 60. Forexample, ring 78 may be attached to frame 60 at troughs 62. For someapplications, ring 78 is stitched to downstream end 36 of valve body 32by stiches 99 that wrap around the ring (i.e., through the opening ofthe ring and around the outside of the ring) but do not pierce the ring(i.e., the material of the ring).

Typically, ring 78 covers downstream end 26 of the implant (e.g., coversthe frames at the downstream end). It is hypothesized by the inventorsthat ring 78 advantageously protects tissue (e.g., native leafletsand/or chordae tendineae) from becoming damaged by downstream end 26 ofimplant 20. There is therefore provided, in accordance with someapplications of the invention, apparatus comprising:

-   -   a valve body, having an upstream end and a downstream end,        shaped to define a lumen from the upstream end to the downstream        end, the lumen defining a longitudinal axis of the prosthetic        valve, and the downstream end of the valve body having;    -   a fabric liner, lining the lumen;    -   a valve member, disposed within the lumen of the valve body; and    -   a polytetrafluoroethylene ring coupled to the downstream end of        the valve body such that the ring circumscribes the lumen at the        downstream end of the valve body.

Reference is made to FIGS. 3A-F, which are schematic illustrationsshowing the implantation of implant 20 at a native valve 10 of a heart 4of a subject, in accordance with some applications of the invention.Valve 10 is shown as a mitral valve of the subject, disposed between aleft atrium 6 and a left ventricle 8 of the subject. However, implant 20may be implanted at another heart valve of the subject, mutatismutandis. Similarly, although FIGS. 3A-F show implant 20 being deliveredtransseptally via a sheath 88, the implant may alternatively bedelivered by any other suitable route, such as transatrially, ortransapically.

Implant 20 is delivered, in its compressed state, to native valve 10using a delivery tool 160 that is operable from outside the subject(FIG. 3A). Tool 160 typically comprises an extracorporeal controller 162(e.g., comprising a handle) at a proximal end of the tool, and a shaft164 extending from the controller to a distal portion of the tool. Atthe distal portion of tool 160, the tool typically comprises a capsule170 comprising one or more capsule portions 172, 174 (described below),and a mount 166. Mount 166 is coupled (typically fixed) to shaft 164.Controller 162 is operable to control deployment of implant 20 bytransitioning the tool between a delivery state (FIG. 3A), anintermediate state (FIG. 3E), and an open state (FIG. 3F). Typically,implant 20 is delivered within capsule 170 of tool 160 in its deliverystate, the capsule retaining the implant in the compressed state.Implant 20 typically comprises one or more appendages 80 at downstreamend 26, each appendage typically shaped to define a catch or otherbulbous element at the end of the appendage, and to engage mount 166,e.g., by becoming disposed within notches in the mount. Appendages 80are typically defined by valve frame 30, but may alternatively bedefined by outer frame 60. Capsule 170 retains appendages 80 engagedwith mount 166 by retaining implant 20 (especially downstream end 26thereof) in its compressed state. A transseptal approach, such as atransfemoral approach, is shown. At this stage, frame assembly 22 ofimplant 20 is as shown in FIG. 2.

Subsequently, flanges 54 are deployed—i.e., are allowed to protruderadially outward, e.g., by releasing them from capsule 170 (FIG. 3B).For example, and as shown, capsule 170 may comprise a distalcapsule-portion 172 and a proximal capsule-portion 174, and the distalcapsule-portion may be moved distally with respect to implant 20, so asto expose flanges 54 while continuing to restrain upstream end 24 anddownstream end 26 of implant 20. In FIG. 3B, upstream support portion 40(e.g., arms 46) is disposed within capsule-portion 174, and downstreamend 36 of tubular portion 32 is disposed within capsule-portion 172.

Typically, and as shown in FIGS. 3A-B, tool 160 is positioned such thatwhen flanges 54 are deployed, they are deployed within atrium 6 and/orbetween leaflets 12 of the subject. Subsequently, the tool is moveddownstream (distally, for a transseptal approach) until the leaflets areobserved to coapt upstream of flanges 54 (FIG. 3C). It is hypothesizedby the inventors that this reduces how far into ventricle 8 the flangesbecome disposed, and therefore reduces the distance that the deployedflanges must be moved in an upstream direction in order to subsequentlyengage the leaflets, and therefore reduces the likelihood ofinadvertently or prematurely ensnaring tissue such as chordae tendineae.This is described in more detail, mutatis mutandis, in WO 2016/125160 toHariton et al., filed Feb. 3, 2016, which is incorporated herein byreference.

Alternatively, flanges 54 may be initially deployed within ventricle 8.

Subsequently, implant 20 is moved upstream, such that flanges 54 engageleaflets 12 of valve 10 (FIG. 3D).

Subsequently, delivery tool 160 is transitioned into its intermediatestate, thereby allowing implant 20 to assume a partially-expanded statein which upstream support portion 40 is expanded, e.g., by releasing theupstream support portion from capsule 170 (FIG. 3E). For example, and asshown, proximal capsule-portion 174 may be moved proximally with respectto mount 166 and/or implant 20, so as to expose upstream support portion40 (e.g., arms 46). Typically, in this state, upstream support portion40 has expanded to have a diameter that is at least 80 percent (e.g., atleast 90 percent, e.g., at least 95 percent) of its diameter in theexpanded state of implant 20 (e.g., the diameter after implantation iscomplete), while downstream end 26 of the implant remains compressed.For some applications, in the partially-expanded state, upstream supportportion 40 has expanded to its fully-expanded diameter. That is,downstream end 36 of tubular portion 32 remaining disposed withincapsule-portion 172 typically does not inhibit, by more than 20 percent,if at all, the expansion of upstream support portion 40. However, in thepartially-expanded state of implant 20, legs 50 are partially inhibitedfrom expanding, such that each leg-tip 68 is radially aligned withconcave region 152. That is, each leg-tip 68 is disposed radiallybetween concave-region inner radius r1 and concave-region outer radiusr2.

In the intermediate state, leaflets 12 of native valve 10 are sandwichedbetween upstream support portion 40 (e.g., annular sheet 25 thereof) andlegs 50 (e.g., flanges 54 thereof). It is to be noted that appendages 80remain engaged with mount 166.

Subsequently, delivery tool 160 is transitioned into its open state,thereby allowing implant 20 to expand toward its expanded state (i.e.,such that tubular portion 32 widens to its fully-expanded state) (FIG.3F). For example, capsule-portion 172 may be moved distally with respectto mount 166 and/or implant 20. The resulting expansion of downstreamend 26 of implant 20 disengages appendages 80, and thereby implant 20 asa whole, from mount 166. Appendages 80 are not visible in FIG. 3F (orFIG. 3C) because they are obscured by ring 78.

In the expanded state of implant 20, each leg-tip 68 is radially alignedwith convex region 154. That is, each leg-tip 68 is disposed radiallybetween convex-region inner radius r3 and convex-region outer radius r4.This is also illustrated in FIG. 1C.

Tool 160 (e.g., capsule-portion 172 thereof) may then be withdrawn vialumen 38 of implant 20, and removed from the body of the subject.

Reference is made to FIGS. 4, and 5A-C, which are schematicillustrations of implants, in accordance with some applications of theinvention. FIG. 4 shows an implant 120. FIG. 5A shows an implant 220,FIG. 5B shows a frame assembly 222 of implant 220 after shape-setting,and FIG. 5C shows a valve frame 230 of frame assembly 222 prior toshape-setting (i.e., the shape-set valve-frame structure).

Implants 120 and 220 are typically the same as implant 20, describedhereinabove, except where noted. Sheeting 23 forms annular sheet 25 thatis disposed over and typically stitched to arms 46. Implant 120 therebycomprises valve body 32 (e.g., as described hereinabove), and anupstream support portion 140 that itself comprises arms 46 and annularsheet 25. Similarly, implant 220 comprises valve body 32 and an upstreamsupport portion 240 that itself comprises arms 46 and annular sheet 25.

Implants 120 and 220 each further comprises a respective plurality ofelongate projections 146 or 246. Whereas arms 46 are covered by sheeting23, the projections extend in an upstream direction through sheeting 23.For some applications, and as shown for projections 146, the projectionsextend through annular sheet 25. For some applications, and as shown forprojections 246, the projections extend between annular sheet 25, and aportion of sheeting 23 that lines valve body 32 (e.g., at a seam wherethese two portions of sheeting 23 are joined). The projections and arms46 are both configured to be positioned in atrium 6 of the heart. Forsome applications, and as shown for projections 146, the projectionsextend through annular sheet 25.

It is to be noted that projection 146 and 246 are distinct fromappendages 80, which are disposed at the other end of the valve body.

Each projection terminates in a nub 148 or 248 that facilitates snaringof the projection using a transcatheter snare, lasso, or similar tool.It is to be understood that the shapes shown for the nubs are merelyexamples, and that the scope of the invention includes any suitablyshaped nub. It is hypothesized by the inventors that the projectionsfacilitate repositioning and/or retrieval of the implant during and/orafter implantation, using a snare, lasso, or similar tool. Theprojections are typically positioned and/or shaped such that nubs 148 or248 are not in contact with annular sheet 25 or atrial tissue (e.g., aredisposed at least 5 mm away (e.g., 5-25 mm away) from annular sheet 25or atrial tissue). For some applications, and as shown for projections146 of implant 120, the projections curve outwards and then inwardstoward the central longitudinal axis of the implant (i.e., are shaped tobe concave toward the axis). For some applications, and as shown forprojections 246 of implant 220, the projections do not extend radiallyoutward from the valve body. Projections 246 typically extend axially inan upstream direction away from the valve body (i.e., generally parallelto axis ax1, i.e., within 10 degrees of axis ax1).

Regarding implant 120 (FIG. 4), projections 146 extend from sites 35 ina similar way to arms 46. Projections 146 may be structurally similar toarms 46, and may even be identically cut when frame 30 is initially cutfrom the original metal tube (i.e., in the raw valve-frame structure).However, projections 146 have a different curvature to arms 46 (e.g.,they may be bent differently post-cutting), and are curved such thatthey extend through annular sheet 25. Whereas at least some of arms 46typically reach and press against the atrial wall, projections 146 aretypically shaped such that nubs 148 are not in contact with the atrialwall. Typically, each projection 146 replaces an arm 46, such that thecumulative sum of arms and projections is twelve. FIG. 4 shows anembodiment comprising six arms 46 and six projections 146, but the scopeof the invention includes other ratios, such as nine arms 46 and threeprojections 146.

FIG. 5A shows implant 220, comprising a frame assembly 222, leaflets 58,and sheeting 23. FIG. 5B shows frame assembly 222 alone, the frameassembly comprising (i) a valve frame 230 that defines valve body 32,and (ii) an outer frame 260. FIG. 5C shows the basic structure of valveframe 230, as it is initially cut from a tube (typically a metallictube, such as a Nitinol tube), e.g., before the frame is shape-set intothe shape shown in FIG. 5B. Although this basic structure is tubular,FIG. 5C depicts the structure two-dimensionally, as though the cut-outstructure were cut longitudinally, and unrolled to become flat.

Except where noted, frame assembly 222, valve frame 230, and outer frame260 are typically identical to frame assembly 22, valve frame 30, andouter frame 60, mutatis mutandis. For some applications, implant 220 isidentical to implant 20 except for projections 246.

In contrast to projections 146 of implant 120, each projection 246 ofimplant 220 extends from a respective site 37 that is at the upstreamextremity (i.e., peak) of a respective first-row cell of upstream row 29a of valve body 32 (i.e., from upstream end 34 of the valve body).Projections 246 thereby alternate with, rather than replace, arms 46.Therefore, it is possible for implant 220 to comprise projections 246 inaddition to twelve arms 46. Implant 220 may comprise an equal number ofprojections 246 and arms 46, but typically, the implant comprises fewerprojections than arms. For example, implant 220 may comprise half asmany, or fewer, projections 246 than arms 46—e.g., a third as many, or aquarter as many projections as arms. Projections 246 and arms 46 aretypically evenly distributed circumferentially, and therefore typicallyat least two arms (e.g., at least three arms, such as at least fourarms) are disposed circumferentially between each projection and each ofits circumferentially-neighboring projections. FIGS. 5A-C show implant220 comprising three projections 246 and twelve arms 46, with four armsdisposed circumferentially between each projection and each of itscircumferentially-neighboring projections. FIGS. 11A-B, describedhereinbelow, show an implant in which three arms are disposedcircumferentially between each projection and each of itscircumferentially-neighboring projections.

Each projection 246 has a projection-length d13, measured from theupstream extremity of the respective first-row cell (i.e., from site37). Each of the arms has an arm-length d14, measured from the upstreamextremity of the respective second-row cell (i.e., site 35). Arm-lengthd14 is greater than projection-length d13 (e.g., 2-20 times greater,e.g., 4-20 times greater, such as 4-10 times greater). For someapplications, arm-length d14 is 20-28 mm, such as 22-26 mm (e.g., 22-23mm, 23.5-24.5 mm, or 25-26 mm). For some applications, projection-lengthd13 is 2-10 mm (e.g., 3-8 mm, e.g., 4-6 mm, such as about 5 mm).

Typically, each arm 46 (i) has a narrow portion 46 a that is attachedto, and extends from, the upstream extremity of the respectivesecond-row cell, and (ii) at a widening zone 46 b, widens into a wideportion 46 c that extends from the narrow portion, and is wider than thenarrow portion. Narrow portion 46 a has a narrow-portion length d20 thatis typically at least 30 percent of arm-length d14 (e.g., at least 40percent, such as 40-80 percent, such as 40-60 percent). Wide portion 46c has a wide-portion length that is at least 30 percent of arm-lengthd14 (e.g., at least 40 percent, such as 40-80 percent, such as 40-60percent).

Wide portion 46 c has a width d15 that is typically 1.5-6 times greater(e.g., 2-4 times greater, such as 2.5-3.5 times greater) than a widthd16 of narrow portion 46 a. For some applications width d15 is 1-2 mm(e.g., 1.4-1.8 mm, such as 1.6 mm). Width d16 is typically 0.2-0.8 mm(e.g., 0.4-0.6 mm, such as 0.5 mm). It is to be noted that, althoughindividual parts of arm 46 within portion 46 c may be narrower thanwithin portion 46 a, these individual parts form a back-and-forthpattern that results in wide portion 46 c being, overall, wider thannarrow portion 46 a. Typically, wide portion 46 c is more flexible, inat least one plane, than narrow portion 46 a. Therefore, wide portion 46c is also a flexible portion of arm 46.

Each projection 246 has a width d17 that is typically 0.2-0.8 mm (e.g.,0.4-0.6 mm, such as 0.5 mm). Each nub has a nub-width d18 that istypically 1-2 mm (e.g., 1.4-1.8 mm, such as 1.6 mm), and a nub-lengthd19 that is typically 0.5-1 mm (e.g., 0.7-0.9 mm, such as 0.8 mm). Wideportion 46 c is typically at least 3 times (e.g., at least 10 times)longer than nub-length d19.

As described hereinabove, the valve frame is typically monolithic, cutfrom a single tube. Typically, and as shown in FIG. 5C, while valveframe 230 is in its raw valve-frame structure (e.g., describedhereinabove with reference to FIGS. 1A-E, mutatis mutandis), nubs 248are disposed between arms 46. As shown in FIG. 5C, arms 46 andprojections 246 may be dimensioned such that, while valve frame 230 isin its raw valve-frame structure, nubs 248 are disposed between narrowportions 46 a of arms 46. That is, nubs 248 may be disposed axiallycloser than wide portion 46 c to valve body 32. Thereby, arms 46 andprojections 246 efficiently fit adjacently to each other within a singlecutout from tube of a particular diameter. Narrow-portion length d20 istypically greater than projection-length d13 (e.g., at least 1.5 timesgreater, such as 1.5-3 times greater).

Reference is now made to FIG. 6, which shows the basic structure of avariant 230 a of valve frame 230, in accordance with some applicationsof the invention. FIG. 6 shows variant 230 a as it is initially cut froma tube (typically a metallic tube, such as a Nitinol tube), e.g., beforethe frame is shape-set. FIG. 6 shows a two-dimensional view, as thoughthe cut-out structure were cut longitudinally, and unrolled to becomeflat. Similarly to with frame 230 (FIG. 5C), nubs 248 of variant 230 aare disposed between arms 46. However, projections 246 a of variant 230a are longer than projections 246 of frame 230, and nubs 248 a aretherefore disposed between wide portions 46 c of arms 46. In order toaccommodate this, in frame 230 a, at least the arms 46 that are adjacentto nubs 248 a are deflected circumferentially (which is representedtwo-dimensionally as being laterally deflected) compared to theirpositions in frame 230, and are typically unevenly spaced. Duringsubsequent shape setting, arms 46 are typically circumferentiallydisplaced, e.g., such that they are evenly spaced. Variant 230 a may beused in place of any other valve frame described herein, mutatismutandis. Similarly, variant 230 a may be used in combination with othertechnologies described herein, mutatis mutandis.

Reference is made to FIG. 7, which is a schematic illustration of anouter frame 60 a, in accordance with some applications of the invention.Outer frame 60 a is typically identical to outer frame 60 except thatpeaks 64 a of frame 60 a have a larger radius of curvature than do peaks64 of frame 60. Outer frame 60 a may be used in place of any other outerframe described herein, mutatis mutandis. Similarly, frame 60 a may beused in combination with other technologies described herein, mutatismutandis.

Reference is made to FIG. 8, which is a schematic illustration of aframe assembly 22 b, in accordance with some applications of theinvention. Frame assembly 22 b comprises a valve frame 30 b and an outerframe 60 b. Except where noted, frame assembly 22 b, valve frame 30 b,and outer frame 60 b are as described for frame assembly 22, valve frame30, and outer frame 60, respectively.

Outer frame 60 b comprises (or defines) (1) a first (e.g., upstream)ring 74 b defined by a pattern of alternating first-ring peaks andfirst-ring troughs, (2) a second (e.g., downstream) ring 76 b defined bya pattern of alternating second-ring peaks and second-ring troughs, anda plurality of legs 50, each of the legs coupled to the first ring andthe second ring, and extending radially outward.

Valve frame 30 b comprises a tubular portion (e.g., a tubular frame)that has a cellular structure defined by a plurality of metallicelements with spaces therebetween a e.g., as described for valve frame30, mutatis mutandis.

The cellular structure of the valve frames described herein may also beviewed as defining rings of alternating peaks and troughs, the ringscircumscribing the longitudinal axis of the implant. Whereas thewaveform (i.e., the peak-trough waveform) of the rings of the outerframe are in phase with each other, the phase of the waveform of therings of the valve frame typically alternate with respect to each other.That is, for the valve frame, the waveform of one ring is out of phase(e.g., is in antiphase) with that of its axially-adjacent rings. Forexample, and with reference to FIG. 1B, valve frame 30 defines a first(e.g., upstream) ring 182, a second (e.g., middle) ring 184, and a third(e.g., downstream) ring 186, and ring 184 is in antiphase with rings 182and 184. Valve frame 30 b similarly defines a first (e.g., upstream)ring 182 b, a second (e.g., middle) ring 184 b, and a third (e.g.,downstream) ring 186 b, and ring 184 b is in antiphase with rings 182 band 184 b.

Typically, and as shown for each of the implants described herein, whenthe frame assembly is assembled, (1) the waveform of one of outer framerings is in-phase with the waveform of the inner frame ring with whichit is axially aligned, and (2) the waveform of one of outer frame ringsis out of phase (e.g., is in antiphase) with the waveform of the innerframe ring with which it is axially aligned. For example, and withreference to FIG. 1C, ring 74 is in-phase with the ring of the innerframe with which it is axially aligned (ring 184), whereas ring 76 is inantiphase with the ring of the inner frame with which it is axiallyaligned (ring 186). Similarly, for frame assembly 22 b, ring 74 b isin-phase with the ring of the inner frame with which it is axiallyaligned (ring 184 b), whereas ring 76 b is in antiphase with the ring ofthe inner frame with which it is axially aligned (ring 186 b).

Because ring 76 b is in antiphase with ring 186 b, the peaks of ring 76b are not disposed directly radially outward from respective parts offrame 30 b, and therefore are not in contact with frame 30 b. However,despite ring 74 b being in phase with ring 184 b, and the peaks of ring74 b being disposed directly radially outward from respective parts offrame 30 b, the peaks of ring 74 b are also not in contact with frame 30b. That is, frame assembly 22 defines a radial gap 188 between frames 30and 60 at the peaks of ring 74 b. Typically, therefore, none of thepeaks of the rings of frame 60 b is in contact with inner frame 30 b. Incontrast, for frame assembly 22, although the peaks of ring 76 are notin contact with frame 30, the peaks of ring 74 typically are in contactwith frame 30.

The features of frame assembly 22 b may be used in combination withother implants described herein. For example, other frame assembliesdescribed herein may be shaped to define gap 188, mutatis mutandis.

Reference is made to FIGS. 9A-B, which are schematic illustrations of aninner frame 330 a, and an implant 320 a comprising inner frame 330 a, inaccordance with some applications of the invention. Inner frame 330 amay be used in place of other inner frames of implants described herein,mutatis mutandis. Similarly, frame 330 a may be used in combination withother technologies described herein, mutatis mutandis. Inner frame 330 acomprises a valve body (which is a generally tubular portion) 332 a thathas an upstream end 334 a and a downstream end 336 a, and is shaped todefine a lumen through the valve body from its upstream end to itsdownstream end. Valve frame 330 a further comprises a plurality of arms46, each of which, in the expanded state, extends radially outward fromvalve body 332 a.

Valve body 332 a has a cellular structure defined by a plurality ofjoists 28 connected at a plurality of nodes 102, the joists and nodesdelimiting cells of the cellular structure. Except where noted, innerframe 330 a is generally the same as inner frame 230 (or inner frame30), mutatis mutandis, and valve body 332 a is generally the same asvalve body 32, mutatis mutandis. Compared to valve body 32, valve body332 a comprises additional joists 28, which are hypothesized by theinventors to increase strength and rigidity. In particular, theadditional joists are hypothesized by the inventors to increase theresistance of the valve body to compression toward axis ax1, includingresistance to circumferential compression (e.g., compression that wouldotherwise reduce the diameter of the valve body, but that would retainthe valve body in a generally cylindrical shape) and localizedcompression (e.g., compression that would otherwise reduce the diameterof the valve body at only certain locations, causing the valve body tobecome more oval in transverse cross-section).

Referring back to FIGS. 1A-B, the cellular structure of valve body 32 issuch that its nodes 100 typically connect 2-4 of its joists. Forexample, a node 100 a connects two joists, and a node 100 b connectsfour joists. (In this context, neither arms 46 nor projections 246 arejoists of the valve body's cellular structure, and so sites 35 and 34are also nodes that connect 2-4 joists.) In contrast, the cellularstructure of valve body 332 a is such that some of its nodes 102 areminor nodes 104, and some are major nodes 106. Minor nodes 104 connect2-4 joists, whereas major nodes 106 connect 6-8 joists. Typically, andas shown, major nodes 106 connect 6 joists (again, excluding arms 46,which are not joists of the valve body's cellular structure). Typically,and as shown, minor nodes 104 connect 2 joists. Therefore, for someapplications, none of the nodes 102 of the cellular structure of valvebody 332 a connects 4 joists.

Similarly to valve body 32 of frame 30, the cells of the cellularstructure of valve body 332 a comprise a first circumferential row 109 aof cells, and a second circumferential row 109 b of cells. That is, row109 a is a row of first-row cells, and row 109 b is a row of second-rowcells. Each of the cells of row 109 a is connected to each of itscircumferentially-adjacent first-row cells at a respective major node106. Typically, and as shown, each of the cells of row 109 a islongitudinally delimited by two minor nodes 104 (i.e., the upstream endand the downstream end of each cell is at a respective minor node). Itis to be noted that, typically, each of the cells of row 109 a is notconnected to another cell at these minor nodes 104 (i.e., the minornodes that longitudinally delimit the first-row cell).

Each of the cells of row 109 b is connected to each of itscircumferentially-adjacent second-row cells at a respective major node106. Typically, and as shown, each of the cells of row 109 b islongitudinally delimited by at least one major node 106 (e.g., isdelimited by one major node at an upstream end of the cell). Typically,and as shown, each of the cells of row 109 b is also longitudinallydelimited by a minor node 104 (e.g., at a downstream end of the cell).For some applications, and as shown, each of the major nodes 106 atwhich circumferentially-adjacent first-row cells are connected is alsothe major node that longitudinally-delimits a respective second-row cell(e.g., at the upstream end of the second-row cell). In the exampleshown, that common major node 106 is also site 35, at which arms 46 areattached to the valve body.

The cells of the cellular structure of valve body 332 a are typicallydelimited by exactly four nodes 102.

Frame 330 a defines coupling elements 31, which are fixed to couplingelements 61 of frame 60 at coupling points, as described hereinabove forframe assembly 22, mutatis mutandis. For some applications, and asshown, coupling elements 31 are defined by respective major nodes 106.Therefore, for some applications, a frame assembly comprises (i) innerframe 330 a that defines valve body 332 a, and (ii) an outer frame(e.g., frame 60) that circumscribes the valve body, and is coupled tothe inner frame by being fixed to major nodes of the valve body. Forsuch applications, coupling elements 31 are typically defined by themajor nodes at which circumferentially-adjacent second-row cells areconnected.

For some applications, and as shown, valve body 332 a is defined byexactly two stacked, tessellated rows 109 of cells. That is, typically,first row 109 a is the most upstream row, second row 108 b is the mostdownstream row, and these two rows are tessellated with each other.Therefore, for some applications, all the cells of the cellularstructure of valve body 332 a are either first-row cells or second-rowcells.

Valve body 332 a may be described as comprising pairs 108 of joists 28that run generally parallel to each other. In the expanded state of thevalve body (i.e., the state shown in FIG. 7) the joists 28 of each pair108 are disposed 0.1-1 mm (e.g., 0.25-0.9 mm, such as 0.25-0.65 mm) fromeach other. Although the joists 28 of each pair 108 run generallyparallel to each other, they typically only share one node 102 incommon. That shared common node is typically a major node 106. That is,at a first end of each pair 108, both joists 28 are typically connectedto each other at a major node. In some cases, at a second end of eachpair 108, one of the joists connects to another major node 106, but theother joist connects to a minor node 104 that is disposed a distance d12away from the major node at the second end of the pair. In other cases,at the second end of each pair 108, one of the joists connects to afirst minor node, and the other joist connects to another minor nodethat is disposed a distance d12 away from the first minor node. Distanced12 is typically 0.1-1 mm (e.g., 0.25-0.9 mm, such as 0.25-0.65 mm).

For some applications, and as shown, the arrangement of joists 28 inpairs 108 results in the joists that delimit the cells of first row 109a not delimiting the cells of second row 109 b. That is, for someapplications, no individual joist 28 delimits both a first-row cell anda second-row cell.

Another aspect of valve body 332 a is as follows: Major nodes 106 aretypically arranged in major-node rows, each major-node rowcircumscribing longitudinal axis ax1 at a respective major-node-rowlongitudinal site, and minor nodes 104 are typically arranged inminor-node rows, each minor-node row circumscribing the longitudinalaxis at a respective minor-node-row longitudinal site. Along at leastpart of axis ax1, the minor-node-row longitudinal sites alternate withthe major-node-row longitudinal sites. For some applications, along atleast this part of axis ax1, at least 3 minor-node-row longitudinalsites alternate with at least 2 major-node-row longitudinal sites, e.g.,in the order minor-major-minor-major-minor, as shown.

Reference is now made to FIGS. 10A-B, which are schematic illustrationsof an inner frame 330 b, and an implant 320 b comprising inner frame 330b, in accordance with some applications of the invention. Inner frame330 b may be used in place of other inner frames of implants describedherein, mutatis mutandis.

Inner frame 330 b comprises a valve body (which is a generally tubularportion) 332 b that has an upstream end 334 b and a downstream end 336b, and is shaped to define a lumen through the valve body from itsupstream end to its downstream end. Valve frame 330 b further comprisesa plurality of arms 46, each of which, in the expanded state, extendsradially outward from valve body 332 b. Inner frame 330 b is typicallythe same as inner frame 330 a, except where noted. Compared to innerframe 330 a, inner frame 330 b comprises additional joists 28 atupstream end 334 b. That is, in contrast to inner frame 330 a, for innerframe 330 b pairs 108 of joists are also disposed at the upstream sideof the upstream row of cells.

In frame 330 a, sites 37 are coincident with the upstream extremity of arespective upstream-row cell. In contrast, in frame 330 b, sites 37 arenot coincident with the upstream extremity of a respective upstream-rowcell. Rather, sites 37 are coincident with a minor node that joins thejoists that are paired with (e.g., that are parallel with) the joists ofthe respective upstream-row cell.

Implant 320 b is typically the same as implant 320 a, except that itcomprises inner frame 330 b instead of inner frame 330 a.

Reference is now made to FIGS. 11A-B, which are schematic illustrationsof an inner frame 330 c, and an implant 320 c comprising inner frame 330c, in accordance with some applications of the invention. Inner frame330 c may be used in place of other inner frames of implants describedherein, mutatis mutandis.

Inner frame 330 c comprises a valve body (which is a generally tubularportion) 332 c that has an upstream end 334 c and a downstream end 336c, and is shaped to define a lumen through the valve body from itsupstream end to its downstream end. Valve frame 330 c further comprisesa plurality of arms 46, each of which, in the expanded state, extendsradially outward from valve body 332 c. Inner frame 330 c is typicallythe same as inner frame 330 b, except where noted.

In general, for implants having an expandable cellular structure, suchas the valve bodies described herein, for a given size of the implant, acellular structure that defines fewer, larger cells, advantageouslyfacilitates radial compression (i.e., “crimping”) to a smaller diameterthan does a comparable cellular structure that defines more, smallercells. However, this is typically at the expense of strength andrigidity of the expanded valve. As described hereinabove, the presenceof additional joists 28 (e.g., in inner frames 330 a, 330 b, and 330 c)to form pairs 108 is hypothesized to increase strength and rigidity, inparticular with respect to compression toward the central longitudinalaxis. As a result, it is further hypothesized by the inventors thatusing such a paired joist cellular structure facilitates reducing thenumber, and increasing the size, of the cells of the valve body, inorder to achieve a valve body that is radially compressible to a smallerdiameter while maintaining sufficient strength and rigidity.

Accordingly, valve body 332 c of inner frame 330 c has fewer, largercells compared to valve body 32 of inner frame 30, and is thereforeradially compressible to a smaller diameter. Whereas each row of cellsof valve body 32 includes 12 cells, each row of cells of valve body 332c includes 9 cells. More generally, whereas the rotationally-symmetricalpattern of valve body 32 has 12 repeats (e.g., 12 cells per cell row, 12minor nodes per minor-node row, 12 major nodes per major-node row, 12coupling elements, 12 arms 46), the rotationally-symmetrical pattern ofvalve body 332 c has only 9 repeats. (Both valve body 32 and valve body332 c typically have 3 appendages 80 and 3 projections 246.) Both valvebody 32 and valve body 332 c define two rows of cells. Therefore,whereas valve body 32 defines 24 cells in total, valve body 332 cdefines 18 cells in total. Whereas valve body 32 defines exactly 24major nodes, valve body 332 c defines exactly 18 major nodes.

For some applications, and as shown, inner frame 330 c comprisesadditional joists 28 at upstream end 334 c (e.g., similarly to innerframe 330 b). That is, for such applications, pairs 108 of joists aretypically also disposed at the upstream side of the upstream row ofcells of inner frame 330 c. For such applications, implant 320 c istypically the same as implant 320 b, except that implant 320 c comprises9 rotationally-symmetrical repeats, rather than 12.

For some applications, inner frame 330 c does not comprise additionaljoists 28 at upstream end 334 c, and is instead more like inner frame330 a in this regard.

Reference is again made to FIGS. 9A-11B. It is to be noted that althoughthe above-described arrangements of joists connected at major and minornodes are described in the context of a prosthetic heart valve, thescope of the invention includes using such arrangements in otherimplants or components thereof that comprise a cellular structure, suchas stents.

Reference is made to FIGS. 12A-H, which are schematic illustrations of atechnique for use with a frame of a prosthetic valve, in accordance withsome applications of the invention. The technique is for augmenting atissue-engaging flange of the frame with a soft pad 300. To illustratethe technique, FIGS. 12A-H show the technique being used to augmentflanges 54 of outer frame 60 with soft pads 300, but it is to be notedthat the technique may be used with any suitable frame, mutatismutandis.

FIG. 12A shows frame 60, which has tissue-engaging flanges 54. A model302 of a soft pad 300 with which each flange 54 is to be augmented isaffixed to the respective flange (FIG. 12B). Subsequently, a mold 304 isformed by (i) positioning frame 60 such that models 302 are supportedwithin a fluid 310 f of a first substance 310 while the first substancesolidifies, and (ii) subsequently, removing the models from the firstsubstance, leaving a cavity in the solidified first substance. Forexample, and as shown in FIGS. 12C-E, a bath 306 of fluid 310 f may beprepared, and frame 60 may be inverted and lowered into the bath suchthat models 302 are supported within the fluid (FIG. 12C). Firstsubstance 310 is allowed to solidify into solidified first substance 310s (FIG. 12D). Subsequently, frame 60 is withdrawn from the bath, therebyremoving models 302 from solidified first substance 310 s, such thateach model leaves a respective cavity 308 in solidified first substance310 s (FIG. 12E).

Models 302 are then removed from flanges 54 (FIG. 12F). Pads 300 arethen formed by: (i) placing flanges 54 in contact with a secondsubstance 312 by repositioning the frame such that each flange issupported within a respective cavity 308, and introducing a fluid 312 fof the second substance to the cavity (FIG. 12G), and (ii) while theflange remains in contact with the second substance, allowing the secondsubstance to solidify into solidified second substance 312 s and tobecome affixed to the flange. Subsequently, flanges 54 are removed fromcavities 308 with formed pads 300 (comprising solidified secondsubstance 312 s) affixed to the flanges (FIG. 12H).

The technique described with reference to FIGS. 12A-H may be used with aframe that has a single tissue-engaging flange. However, as shown, thetechnique is typically used with a frame that has a plurality offlanges, e.g., to augment all the flanges simultaneously. It is to benoted that flanges 54 are not all disposed on the same side of frameassembly 22 (i.e., after frames 30 and 60 have been attached to eachother). For example, flanges 54 are not all at the upstream end of theprosthetic valve or at the downstream end of the prosthetic valve.Rather, they are disposed downstream of the tips of arms 46 and upstreamof downstream end 26. Furthermore, flanges 54 are arrangedcircumferentially around the longitudinal axis of the prosthetic valve.Flanges 54 (and eventually pads 300) are arranged circumferentiallyaround frame 30 longitudinally between the upstream end and thedownstream end of frame 30, exclusive. For some applications, theflanges being not all disposed on the same side might inhibit the use ofthe technique of FIGS. 12A-H to simultaneously augment all of theflanges. For example, it may be difficult to place all of models 302into the fluid first substance, or to place all of flanges 54 into thefluid second substance, without also placing other portions of the frameassembly into the fluid substance. The two-frame nature of frameassembly 22 advantageously allows flanges 54 to be augmented with padsbefore frame 60 is attached to frame 30. Because all of flanges 54 aredisposed at the same side (e.g., the upstream side) of frame 60, theycan all be placed into the fluid substances simultaneously.

An alternative solution is also contemplated by the inventors, in whichan annular bath is positioned circumscribing the central portion of theprosthetic valve or frame assembly, such that all flanges can be placedinto the fluid substances even when the flanges are not all disposed onthe same side of a prosthetic valve or frame assembly.

For some applications, substance 310 and/or substance 312 may be amixture of constituents that is initially fluid upon mixing, and thatsolidifies as the constituents react with each other. For someapplications, fluid substance 310 f and/or fluid substance 312 f isfluid because it is in a molten state, and solidifies as it cools. Whensolidified, second substance 312 is typically soft, flexible, and/orresilient. For some applications, second substance 312 (or at leastsolidified second substance 312 s) is a foam. For some applications,second substance 312 comprises silicone, polyurethane, a thermoplasticelastomer such as Santoprene™, and/or polyether block amide.

For some applications, the techniques described with reference to FIGS.12A-H are alternatively or additionally used, mutatis mutandis, toaugment the downstream end of the implant with one or more pads, e.g.,to serve a similar function to ring 78 described hereinabove.

Reference is made to FIGS. 13A-E, 14A-D, 15A-C, 16A-C, 17, 18A-C, and19, which are schematic illustrations of an implant 420, and steps inthe assembly of the implant, in accordance with some applications of theinvention. In particular, these figures illustrate steps in theattachment of various flexible components to the frame assembly of theimplant, such as steps in the dressing of the frame assembly withvarious sheets of flexible material. Implant 420 is shown as comprisingframe assembly 222, and is typically identical to implant 220 except forwhere described otherwise. However, it is to be noted that the stepsdescribed with reference to FIGS. 13A-18C may be used, mutatis mutandis,to assemble other implants, including the other implants describedherein.

FIGS. 13A-E show flexible components of implant 420. FIGS. 13A-B areperspective and side views, respectively, of a valvular assembly 430,comprising leaflets 58 arranged to serve as a check valve. In valvularassembly 430, each leaflet 58 defines (i) an upstream surface 457, pastwhich blood will flow through implant 420 in an upstream-to-downstreamdirection, and (ii) a downstream surface 459, against which blood willpress when the valvular assembly closes and inhibits blood flow in adownstream-to-upstream direction. Valvular assembly 430 typicallyfurther comprises a liner 427 and/or a plurality of connectors 432.Liner 427 of implant 420 generally corresponds to liner 27 of implant20, mutatis mutandis. Typically, valvular assembly 430 comprises threeleaflets 58 and three connectors 432. Connectors 432 couple the leafletsto each other to form commissures, and are used to secure the leaflets,at the commissures, to frame assembly 222. Connectors 432 are arrangedcircumferentially, and leaflets 58 extend radially inward from theconnectors. For some applications, valvular assembly 430, and connectors432 in particular, are as described in PCT patent applicationpublication WO 2018/029680 to Hariton et al., and/or U.S. patentapplication Ser. No. 15/878,206 to Hariton et al., both of which areincorporated herein by reference.

Each leaflet 58 is attached (e.g., stitched) to liner 427 along a line(e.g., a stitch line) 437. Each leaflet 58 defines a free edge 458,which is typically straight, and at which the leaflet coapts with theother leaflets 58. Stitch line 437 is typically curved. Each leaflettypically defines a curved edge (e.g., an upstream edge) 456 at whichthe leaflet is attached to liner 427. The curve of edge 456 and/orstitch line 437 is concave toward the downstream end of valvularassembly 430, such that edge 456 and/or stitch line 437 (i) becomecloser to the downstream end of the valvular assembly at connectors 432,and (ii) are closest to the upstream end of the valvular assembly aboutmidway circumferentially between the connectors. That is, edge 456 hasan apex about midway circumferentially between connectors 432.

Typically, and as shown, leaflets 58 extend further axially downstream(i.e., downstream with respect to axis ax1) than does liner 427.Therefore, a downstream portion of each leaflet 58 is typicallycircumferentially exposed from liner 427. For some applications, and asshown, liner 427 is shaped to define regions 428 at which a downstreamedge 436 of the liner recedes from the downstream end of valvularassembly 430. At each region 428, more of the respective leaflet 58 iscircumferentially exposed. Each region 428 is typicallycircumferentially aligned with the concavity defined by edge 456 and/orstitch line 437. At regions 428, downstream edge 436 of liner 427 istypically stitched to ring 182 of frame 230. Therefore, for someapplications, the most upstream parts of downstream edge 436 of liner427 are closer to the upstream end of the implant than is the mostdownstream parts of arms 46. As described in more detail hereinbelow, inimplant 420, regions 428 of liner 427 facilitate the provision ofwindows 482 into a pouch 490.

FIG. 13C shows a sheet 440 of flexible material. Typically, and asshown, sheet 440 is provided flat, and in the shape of a major arc of anannulus, having a first arc-end 442 a and a second arc-end 442 b. Sheet440 of implant 420 generally corresponds to annular sheet 25 of implant20, mutatis mutandis.

FIG. 13D shows a sheet 450 of flexible material. Sheet 450 is annular,and defines an inner perimeter 452, an outer perimeter 454, and a radialdimension d21 therebetween.

FIG. 13E shows a sheet 460 of flexible material. Sheet 460 is shaped todefine a belt 462 and a plurality of elongate strips 464. Each strip 464defines a respective central strip-axis ax2, and extends along itsstrip-axis from belt 462 to the end 466 of the strip. Typically, belt462 is linear and defines a belt-axis ax3, and strip-axis ax2 isorthogonal to the belt-axis. Typically, strips 464 are parallel to eachother. Each strip 464 has first and second edges 468 (e.g., a first edge468 a and a second edge 468 b), which extend on either side of axis ax2,between belt 462 and end 466.

As indicated by the reference numeral 23, sheets 440, 450, and 460 mayall be considered components of sheeting 23. For some applications,liner 427, sheet 440, sheet 450, and/or 460 comprise (e.g., consist of)the same material as each other. Typically, sheets 440, 450, and 460 areprovided as flat, and are subsequently shaped during assembly of implant420, e.g., as described hereinbelow.

For applications in which sheet 440 is provided flat and in the shape ofa major arc of an annulus, sheet 440 is shaped into an open frustum byattaching (e.g., stitching) ends 442 a and 442 b together (FIGS. 14A-B).This is represented by a stitch line 444 in FIG. 14B. Alternatively,sheet 440 may be provided in the open frustum shape. The open frustumshape has a greater perimeter 446 at a first base of the frustum, and asmaller perimeter 448 at a second base of the frustum. Perimeter 448defines an opening, and sheet 440 is stitched to arms 46 such that theopening is aligned with the lumen defined by valve body 32 of frame 30(FIG. 14C), and typically such that the sheet covers an upstream side ofthe arms. FIG. 14D shows valvular assembly 430 having been coupled toframe assembly 222. This step may be performed after sheet 440 isstitched to arms 46 (as shown) or beforehand. Valvular assembly 430 isplaced inside valve body 32 of frame 30, and is attached by stitchingconnectors 432 and liner 427 to frame assembly 222. Connectors 432 aretypically stitched to ring 184 and/or ring 186. For some applications,the attachment of connectors 432 to frame assembly 222 is as describedin PCT patent application publication WO 2018/029680 to Hariton et al.,and/or U.S. patent application Ser. No. 15/878,206 to Hariton et al.,both of which are incorporated herein by reference.

Smaller perimeter 448 of sheet 440 is stitched to an upstream edge 434of liner 427, to form a substantially sealed channel through implant420. This stitching is represented by a stitch line 435. Typically, andas shown, projections 246 extend between, and are sandwiched between,perimeter 448 of sheet 440 and upstream edge 434 of liner 427. Upstreamedge 434 is typically circular.

Downstream edge 436 of liner 427 is stitched to valve body 32 of frame30. Typically, downstream edge 436 is shaped and positioned toapproximately conform to rings 182 and 184, and is stitched to theserings.

It is to be noted that throughout this patent application (including thespecification and the claims) stitching of a perimeter or edge of asheet to a perimeter or edge of another sheet, does not necessarily meanthat the sheets are stitched at their absolute edges (i.e., their freeedges). Rather, in this context, the “perimeter” or “edge” also includesthe adjacent area of the sheet, as is understood by one of ordinaryskill in the stitching art, and as is typically required for effectivestitching.

Valvular assembly 430 is typically positioned within frame assembly suchthat the apex of curved edge 456 of each leaflet 58 is disposed axiallyclose to (e.g., axially within 2 mm of, e.g., within 1 mm of) anupstream end 34 of valve body 32. Valvular assembly 430 is alsotypically positioned within frame assembly such that free edge 458 ofeach leaflet 58 is disposed downstream of leg 50.

Subsequently, sheet 450 is attached to frame assembly 222 (FIGS. 15A-C).Outer perimeter 454 of sheet 450 is stitched to greater perimeter 446 ofthe sheet 440 (FIG. 15A). This is represented by stitch line 455.Typically, perimeter 454 is larger than perimeter 446, and is broughtinwards to be stitched to perimeter 446 (e.g., making sheet 450frustoconical), with inner perimeter 452 disposed axially away fromframe assembly 222 (e.g., further axially away than outer perimeter 454from the frame assembly).

Subsequently, sheet 450 is everted by bringing inner perimeter 452toward frame assembly 222, and passing the inner perimeter around thetips of arms 46—i.e., axially past the tips of all of the arms (FIG.15B). Typically, and as shown, arms 46 collectively define an arm-spand23 that is wider than perimeter 452. That is, the tips of arms 46typically define a perimeter that is greater than perimeter 452. Forsome applications, the passage of inner perimeter 452 around the tips ofarms 46 is facilitated by bending (e.g., temporarily) one or more ofarms 46.

Inner perimeter 452 is advanced over at least part of valve body 32toward a downstream end of frame assembly 222, and is stitched in place.Typically, perimeter 452 is advanced between the valve body and legs 50,such that perimeter 452 circumscribes valve body 32, and legs 50 aredisposed radially outside of sheet 450. As described hereinabove, eachleg 50 extends radially outward and in an upstream direction from arespective leg-base 66 to a respective leg-tip 68. Each leg thereforeextends at an acute angle to define a respective cleft 250 between theleg and valve body 32 (e.g., the tubular portion), the cleft open to theupstream direction. Typically, perimeter 452 is tucked into clefts 250,and is stitched into place. Frame assembly 222 defines a distance d22,measured along a straight line, between the ends of arms 46 and clefts250. For clarity, distance d22 may be defined as a distance between (i)an imaginary ring described by the ends of arms 46, and (ii) animaginary ring described by clefts 250.

The dimensions and positioning of sheet 450 defines an inflatable pouch490 that is bounded by sheet 450 (e.g., defining an outer and/ordownstream wall of the pouch), sheet 440 (e.g., defining an upstreamwall of the pouch), and liner 427 (e.g., defining an inner wall of thepouch). Pouch 490 typically circumscribes the longitudinal axis of theimplant and/or the valve body of frame assembly 222 (e.g., the pouch isa cuff), and further typically extends radially outward from the valvebody. Typically, an upstream portion of pouch 490 is attached to valveframe 30 (e.g., and is not attached to outer frame 60), and a downstreamportion of the pouch is attached to the outer frame. As described inmore detail hereinbelow, at least one respective window 482 into pouch490 is defined between each leaflet 58 and perimeter 452.

FIGS. 16A-C show steps in dressing frame assembly 222 with sheet 460, inaccordance with some applications of the invention. Each strip 464 isformed into a respective pocket 478 (FIGS. 16A-B). Each strip is foldedover itself, about a fold-line 463 that is orthogonal to strip-axis ax2,thereby forming (i) a first strip-portion 464 a that extends from belt462 to the fold-line, and (ii) a second strip-portion 464 b that extendsfrom fold-line back toward the belt. First strip-portion 464 a andsecond strip-portion 464 b are stitched together at first edge 468 a andsecond edge 468 b. The resulting pocket 478 is typically elongate, andhas (i) an opening 470 defined at least in part by end 466 of the strip,and (ii) a tip 472 at the fold-line.

For some applications, a soft pad 476 is provided in each pocket 478,typically at tip 472. For some such applications, and as shown in FIG.15B, pad 476 is formed from a piece of foam 474 (e.g., comprisingpolyurethane). Piece of foam 474 may initially be generally cubic. Forsome applications, and as shown, piece of foam 474 is folded to form aniche 477 in pad 476, typically after having been at least partlyflattened by compression. Pad 476 may be introduced into pocket 478before the pocket is fully formed (e.g., as shown), or may besubsequently introduced into the pocket via opening 470.

Alternatively, pads 300 may be used in place of pads 476, and may beadded to flanges 54 as described with reference to FIGS. 12A-H, mutatismutandis.

For applications in which pad 476 is used, each strip-portion 464 a and464 b typically defines a widened region 479 adjacent to fold-line 463,such that when pockets 478 are formed, a receptacle for pad 476 isformed.

Pockets 478 are subsequently slid onto legs 50, and belt 462 is wrappedaround frame assembly 222 downstream of legs 50 (e.g., downstream of theaxial level at which the legs are coupled to the valve body). Belt 462is typically positioned such that it is disposed over the commissures ofleaflets 58 and/or over connectors 432. That is, the belt is typicallywrapped around the frame assembly at an axial level such t Forapplications in which pads 476 are used, flanges 54 of legs 50 aretypically advanced into niches 477 of the pads. Belt 462 (e.g., the edgeof the belt from which pockets 478 extend) is stitched to sheet 450.More specifically, the upstream edge of belt 462 is stitchedcircumferentially to perimeter 452 of sheet 450. This is represented bya stitch line 465. Therefore, once implant 420 is assembled, the edge ofbelt 462 from which pockets 478 extend is an upstream edge of the belt,while the edge that is closest to the downstream end of the implant is adownstream edge of the belt. Legs 50, within pockets 478, extendradially outward from between belt 462 and sheet 450 (e.g., at stitchline 465).

For some applications, tips 472 and/or pads 476 are further secured toflanges 54 by stitching 475, which may pass through a hole 55 (labeledin FIG. 1A) defined in each flange 54. Stitching 475 is visible in FIGS.18A-C.

As shown in FIG. 16C, for some applications, polytetrafluoroethylenering 78 is typically also attached to frame assembly 222. For some suchapplications, in addition to being stitched to frame assembly 222, ring78 is also stitched to belt 462 (e.g., to the edge of the belt oppositepockets 478—i.e., the downstream edge of the belt).

FIG. 17 shows a ribbon 480 being wrapped around the leg-base 66 of eachleg 50, in accordance with some applications of the invention. For someapplications, the ends of ribbon 480 overlap. Ribbons 480 are stitchedin place, but the stitches are typically not disposed in cleft 250. Asshown, ribbons 480 may be stitched to belt 462. Although ribbons 480 areshown being used in combination with pockets 478 (and are thereforewrapped around the pockets at leg-base 66), it is to be noted thatribbons 480 may alternatively be used for applications in which legs 50are generally uncovered. Ribbon 480 covers cleft 250, and ishypothesized by the inventors to reduce a likelihood of tissue (e.g.,leaflet or chordae tissue) from becoming wedged in and/or damaged by thecleft.

FIGS. 18A-C show implant 420 after its assembly. FIG. 18A is an upperperspective view (e.g., showing upstream surfaces of the implant), FIG.18B shows a side view, and FIG. 18C shows a lower perspective view(e.g., showing downstream surfaces of the implant).

As described with reference to FIGS. 3E-F, implant 20 (which comprisesframe assembly 22) is secured in place at the native valve bysandwiching tissue of the native valve between the implant's upstreamsupport portion 40 and flanges 54. Implants that comprise frame assembly222, such as implant 220, are typically secured in the same way, mutatismutandis. Implants that further comprise pouch 490, such as implant 420,are typically secured similarly, but with pouch 490 disposed between theupstream support portion and the tissue of the native valve. Thereforein at least some regions of implant 420, the tissue of the native valveis sandwiched between flanges 54 and pouch 490, e.g., as shown in FIG.19.

Windows 482 open into pouch 490 from the lumen of the valve body. Onceimplant 420 has been implanted at the native valve, windows 482 aredisposed functionally within ventricle 8, whereas at least portions ofpouch 490 are disposed functionally within atrium 6. Therefore, duringventricular systole, ventricular pressure (which is much greater thanatrial pressure) forces blood into pouch 490, thereby inflating thepouch. This inflation presses pouch 490 against the tissue of the nativevalve. It is hypothesized by the inventors that this inhibitsparavalvular leakage of blood, especially during ventricular systole.For example, the pouch may seal a paravalvular gap at the commissures ofthe native valve. For some applications, inflation of pouch 490 squeezestissue of the native valve (e.g., native leaflets) between the pouch andflanges 54. Pouch 490 is typically dimensioned such that if, in aparticular region, tissue is not disposed between a flange 54 and pouch490, inflation of the pouch presses the pouch against the flange.

There is therefore provided, in accordance with an application of thepresent invention, apparatus, comprising:

-   -   a frame assembly (e.g., frame assembly 222) that comprises: (i)        a valve body that circumscribes a longitudinal axis and defines        a lumen along the axis; (ii) a plurality of arms (e.g., arms 46)        that are coupled to the valve body at a first axial level with        respect to the longitudinal axis (e.g., defined by sites 35),        each of the arms extending radially outward from the valve body        to a respective arm-tip; and (iii) a plurality of ventricular        legs (e.g., legs 50) that (a) are coupled to the valve body at a        second axial level with respect to the longitudinal axis (e.g.,        defined by coupling points 52), the second axial level being        downstream of the first axial level, and that (b) extend        radially outward from the valve body and toward the plurality of        arms;    -   a tubular liner (e.g., liner 427) that lines the lumen, and that        has an upstream end and a downstream end;    -   a plurality of prosthetic leaflets (e.g., leaflets 58), disposed        within the lumen, attached to the liner, and arranged to        facilitate one-way upstream-to-downstream fluid flow through the        lumen;    -   a first sheet of flexible material (e.g., sheet 440), the first        sheet having (i) a greater perimeter, and (ii) a smaller        perimeter that defines an opening, the first sheet being        attached to the plurality of arms with the opening aligned with        the lumen of the valve body; and    -   a second sheet of flexible material (e.g., sheet 450):        -   the second sheet having a first perimeter and a second            perimeter,        -   the first perimeter being attached to the greater perimeter            of the first sheet around the greater perimeter of the first            sheet,        -   the second sheet extending from the first perimeter radially            inwards and downstream toward the second perimeter, the            second perimeter circumscribing, and attached to, the valve            body at a third axial level that is downstream of the first            axial level.

The first sheet, the second sheet, and the liner define inflatable pouch490 therebetween, the first sheet defining an upstream wall of thepouch, the second sheet defining a radially-outer wall of the pouch, andthe liner defining a radially-inner wall of the pouch. The apparatusdefines a plurality of windows (e.g., windows 482) from the lumen intothe pouch, each of the windows bounded by the liner at upstream edges ofthe window, and bounded by the second perimeter and/or belt 462 at adownstream edge of the window. Each window 482 is typicallydiscrete—i.e., bounded on all sides, and separate from other windows.For some applications in which downstream edge 436 of liner 427 isstitched to ring 182 of frame 230, the most upstream parts of windows482 are closer to the upstream end of the implant than are the mostdownstream parts of arms 46

Typically, and as shown, pouch 490 circumscribes the valve body ofimplant 420.

Typically, and as shown in FIG. 18C, each window 482 spans more than onecell of the valve body. This is represented by the multiple instances ofreference numeral 482 in FIG. 18C. For some applications, and as shown,each window spans at least partly of five cells of the valve body. Forsome such applications, and as shown, each window spans substantiallyall of two cells (e.g., two cells of row 29 a) and about half (e.g.,40-60 percent) of each of three cells (e.g., three cells of row 29 b).Each window 482 is bounded by liner 427 at an upstream edge of thewindow. Typically, and as shown, the upstream edge of each window 482 isdefined at rings 182 and 184 of valve frame 230, at which region 428 ofliner 427 is stitched to the valve frame. At the downstream edge of eachwindow, the window is bounded by perimeter 452, and also by belt 462.Therefore, at the downstream edge of each window 482, the window may beconsidered to be bounded by stitch line 465.

For some applications, the upstream edge of each window 482 is the shapeof a capital letter M, e.g., with the apices of the letter M at upstreamend 34 of the valve body, and with the vertex of the letter M at a site35. Because region 428 of liner 427 follows, and is stitched to, thejoists of valve frame 230 at region 428 of the liner, it is hypothesizedby the inventors that this arrangement reinforces the upstream edge ofwindow 482, e.g., increasing durability compared to an arrangement inwhich the upstream edge of the window crosses between joists of thevalve frame.

As described hereinabove, sheet 440 typically covers an upstream side ofarms 46. Once pouch 490 has been formed, at least most of each arm 46 istherefore disposed inside the pouch. As also described hereinabove,sheet 440 is stitched to arms 46. Once pouch 490 has been formed, thepouch (i.e., the part of the pouch defined by sheet 440) is thereforestitched to arms 46,

For some applications, a circumferential stitch line 445 is used tostitch sheet 440 to sheet 450 at a radius smaller than the overallradius of upstream support portion 40 (i.e., radially inward from thetips of arms 46), typically sandwiching arms 46 between these twosheets. Stitch line 445 is typically radially aligned with region 154and/or wide (and flexible) portion 46 c of arm 46. This typicallycreates a region 484 in which the portions of sheets 440 and 450 thatare disposed radially outward from stitch line 445 are isolated frompouch 490. For such applications, the ends of arms 46 are thereforetypically disposed in region 484, and are isolated from pouch 490.

For some applications, and as shown, sheet 450 is sufficiently baggythat the sheet (e.g., pouch 490) may extend radially outward beyond arms46, particularly if uninhibited by tissue of the native valve. This maybe achieved by radial dimension d21 of sheet 450 being greater thandistance d22 between the ends arms 46 and clefts 250. For someapplications, dimension d21 is more than 30 percent greater (e.g., morethan 50 percent greater) than distance d22. For example, dimension d21may be 30-100 percent greater (e.g., 30-80 percent greater, e.g., 40-80percent greater, such as 50-70 percent greater) than distance d22. Asshown, pouch 490 may extend radially outward beyond arms 46 irrespectiveof the presence of stitch line 445, which is disposed radially-inwardfrom the ends of arms 46.

Regarding the axial position (i.e., the position along the longitudinalaxis of implant 420) of pouch 490 and windows 482. For someapplications, pouch 490 extends, with respect to the longitudinal axisof implant 420, further upstream than the leaflets. That is, for someapplications, upstream regions of pouch 490 (e.g., those closest toprosthetic valve support 40) are situated further upstream than even theapex of curved edge 456 of leaflets 58. For some applications, and asshown, each of leaflets 58 is attached to liner 427 upstream of windows482. That is, at least the apex of curved edge 456 of leaflets 58 isdisposed upstream of windows 482. Free edge 458 of each leaflet 58 istypically disposed downstream of the third axial level—i.e., the axiallevel at which perimeter 452 of sheet 450 is attached to frame assembly222. That is, leaflets 58 typically extend further downstream than pouch490. For some applications, and as shown, the third axial level (i.e.,the axial level at which perimeter 452 of sheet 450 is attached to frameassembly 222) is upstream of the second axial level (i.e., the axiallevel at which legs 50 are attached to the valve body).

It is to be noted that, whereas liner 427 is disposed on the inside ofvalve body 32, sheet 450 and belt 462 are disposed on the outside of thevalve body. Axially downstream of windows 482, valve body 32 istypically not lined—i.e., no liner is typically disposed betweenleaflets 58 and frame 30. However, belt 462 circumscribes valve body 32and serves a similar function to a liner—channeling fluid through thelumen of the valve body.

It is to be noted that projections 246 are not visible in FIG. 18B. Forsome applications, and as shown, the projection-length of projections246 (e.g., see projection-length d13 in FIG. 5C) is such that theprojections do not extend further upstream than the tips of arms 46. Forsome applications, and as shown, projections 246 extend further upstreamthan the highest part of arms 46 within concave region 152. For someapplications, and as shown, projections 246 extend to an axial heightthat is between (a) that of the tips of arms 46, and (b) that of thehighest part of arms 46 within concave region 152. This is illustratedperhaps most clearly in FIG. 9A, which shows inner frame 330 a, but isapplicable to each of the inner frames described herein, mutatismutandis.

Reference is made to FIGS. 20, and 21A-C, which are schematicillustrations of implant 420, in accordance with some applications ofthe invention. Pouch 490 defines an interior space 500. For someapplications, and as shown, arms 46 and legs 50 (e.g., flanges 54thereof) narrow pouch 490 therebetween to form a narrowed portion 510 ofthe pouch. Narrowed portion 510 typically circumscribes valve body 32and/or the longitudinal axis of the implant—e.g., the narrowed portionbeing annular. This thereby defines (i) an inner portion 502 of theinterior space, radially inward from narrowed portion 510, and in fluidcommunication with lumen 38 of the implant (e.g., via windows 482), and(ii) an outer portion 504 of the interior space, radially outward fromthe narrowed portion, and in fluid communication with inner portion 502via the narrowed portion. At narrowed portion 510 each leg 50 (e.g.,flange 54 thereof) typically pushes sheet 450 (which defines adownstream surface of pouch 490) toward sheet 440 (which defines anupstream surface of the pouch), such as pressing sheet 450 into contactwith sheet 440.

Typically, and as shown, arms 46 and legs 50 alternatecircumferentially. That is, when viewed from above, an arm 46 isdisposed circumferentially on either side of each leg 50, and a leg isdisposed circumferentially on either side of each arm. This isillustrated for implant 22 in FIG. 1D, mutatis mutandis. Forapplications in which arms 46 and legs 50 alternate circumferentially,at narrowed portion 510 each leg 50 (e.g., flange 54 thereof) forms arespective bulge 506 in sheet 440 (i.e., the upstream surface of pouch490) by pressing sheet 450 (i.e., the downstream surface of the pouch)against the upstream surface (see FIG. 18A). Bulges 506 are thereforedisposed circumferentially between arms 46. It is typically the tip ofeach leg 50 that presses into sheet 450, and therefore bulges 506 aretypically compact (e.g., as opposed to being elongate).

It is to be noted that narrowed portion 510 is therefore formed withoutpouch 490 being sandwiched directly between arms 46 and legs 50. It isalso to be noted that, at narrowed portion 510, pouch 490 is stitched toarms 46 but not to legs 50. For some applications, at narrowed portion510, legs 50 extend in an upstream direction past arms 46. (This can beunderstood from FIG. 1C, mutatis mutandis). For some applications, thisconfiguration results in sheet 450 billowing between legs 50, e.g., asindicated by reference numeral 508 in FIG. 18C.

It is to be noted that the configuration described hereinabove exists inimplant 420 even prior to implantation—i.e., even in the absence oftissue captured between arms 46 and flanges 54.

For some applications of the invention, narrowed portion 510 impedesfluid communication between outer portion 504 and inner portion 502 (andthereby between the outer portion and the lumen of the implant). It ishypothesized by the inventors that, for some such applications, thisadvantageously inhibits blood that has entered outer portion 504, fromexiting the outer portion. During ventricular systole, ventricularpressure forces blood through windows 482 into pouch 490 (i.e., innerportion 502 thereof). At least some of this blood typically enters outerportion 504, e.g., due to the relatively high ventricular pressure. Itis hypothesized by the inventors that, at least in part due to narrowedportion 510, during ventricular diastole, pressure in the oppositedirection is insufficient to force as much blood back out of outerportion 504. It is further hypothesized by the inventors that, for someapplications, this results in a net increase in the volume of bloodwithin outer portion 504 during each cardiac cycle, e.g., untilresistance inhibits further inflation of outer portion 504. This isillustrated by the sequence of frames A-F in FIG. 20, which representthe state of implant 420 over time. FIG. 20 shows blood 14 enteringouter portion 504 only after inner portion 502 has become substantiallyfilled (frames C-D), but for some applications blood may begin to enterouter portion 504 earlier.

It is hypothesized by the inventors that such a configuration of pouch490 further improves paravalvular sealing provided by the pouch. It isfurther hypothesized by the inventors that, for some applications of theinvention, such a configuration of pouch 490 facilitates the pouch(e.g., outer portion 504 thereof) conforming to the tissue surroundingimplant 420, and therefore further facilitating sealing. For example,FIGS. 21A-C show implant 420 disposed at native valve 10, when theanatomy of the native valve (e.g., the annulus and/or leaflets) areuneven with respect to the implant. For example, the anatomy itself maybe particularly uneven, or the implant may have been implanted at asub-optimal angle with respect to the anatomy. In the example shown, ata zone 520 a the anatomy is relatively close to upstream support portion40, whereas at a zone 520 b, the anatomy is relatively spaced apart fromthe upstream support portion, e.g., resulting in a gap 522 (FIG. 21A).Over time (e.g., between ten seconds and one hour), outer portion 504fills, in each zone, according to the mechanical constraints of thatregion (FIGS. 21B-C). In the example shown, in zone 520 a outer portion504 inflates with blood until space between upstream support portion 40and the anatomy (e.g., annulus or leaflet tissue) is filled, and theanatomy resists further inflation of the outer portion (FIG. 21B). Inzone 520 b outer portion 504 continues to inflate with blood because, inthis zone, the space between the upstream support portion and theanatomy is larger (FIG. 21C). In this way, it is hypothesized by theinventors that implant 420 advantageously adapts to the native anatomy,providing improved paravalvular sealing.

For some applications, at least one coagulation component 530 isdisposed within outer portion 504, and is configured to promote bloodcoagulation within the outer portion. For some applications, coagulationcomponent 530 is annular and, within outer portion 504, circumscribesthe longitudinal axis of the implant. For some applications, coagulationcomponent 530 comprises a fabric (e.g., comprising polyethyleneterephthalate). For some applications, coagulation component 530comprises polytetrafluoroethylene (e.g., expandedpolytetrafluoroethylene), e.g., in the form of a membrane or ribbon. Forsome applications, coagulation component 530 comprises a metallic (e.g.,nitinol or stainless steel) wire, membrane, or mesh, covered by a fabricor expanded polytetrafluoroethylene. For applications, coagulationcomponent comprises a coagulation-inducing drug coated thereon orembedded therein (e.g., within a fabric). For some applications,coagulation component 530 comprises pericardial tissue (e.g., bovine orporcine).

For some applications of the invention, the scope of the inventionincludes using one or more of the apparatus and techniques described inthis patent application in combination with one or more of the apparatusand techniques described in one or more of the following documents, eachof which is incorporated herein by reference:

-   -   U.S. patent application Ser. No. 15/541,783 to Hariton et al.,        filed Jul. 6, 2017, and entitled “Prosthetic valve with        axially-sliding frames,” which published as US 2018/0014930 (now        U.S. Pat. No. 9,974,651)    -   U.S. patent application Ser. No. 15/668,659 to Hariton et al.,        filed Aug. 3, 2017, and entitled “Techniques for deployment of a        prosthetic valve,” which published as US 2017/0333187    -   U.S. patent application Ser. No. 15/668,559 to Iamberger et al.,        filed Aug. 3, 2017, and entitled “Prosthetic heart valve”    -   U.S. patent application Ser. No. 15/956,956 to Iamberger et al.,        filed Apr. 19, 2018, and entitled “Prosthetic heart valve”    -   PCT patent application IL2018/050725 to Hariton et al., filed        Jul. 4, 2018, and entitled “Prosthetic heart valve”    -   U.S. patent application Ser. No. 16/135,969 to Hariton et al.,        filed Sep. 19, 2018, and entitled, “Prosthetic valve with        inflatable cuff configured for radial extension”    -   U.S. patent application Ser. No. 16/135,979 to Hariton et al.,        filed Sep. 19, 2018, and entitled, “Prosthetic valve with        inflatable cuff configured to fill a volume between atrial and        ventricular tissue anchors”    -   U.S. provisional patent application 62/560,384 to Hariton et        al., filed Sep. 19, 2017, and entitled “Prosthetic valve and        methods of use.”

(Some elements in the present patent application are also described inU.S. 62/560,384, U.S. Ser. No. 16/135,969, or U.S. Ser. No. 16/135,979,but are named differently. For the sake of clarity, element names usedin the present application supersede those used in U.S. 62/560,384, U.S.Ser. No. 16/135,969, or U.S. Ser. No. 16/135,979.)

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

The invention claimed is:
 1. Apparatus, comprising: a frame assembly that comprises: a valve body that circumscribes a longitudinal axis and defines a lumen along the axis; a plurality of upstream arms that are coupled to the valve body at a first axial level with respect to the longitudinal axis, each of the plurality of upstream arms extending radially outward from the valve body to a respective arm-tip; and a plurality of downstream legs that are coupled to the valve body at a second axial level with respect to the longitudinal axis, and that extend radially outward from the valve body and toward the plurality of upstream arms; a plurality of prosthetic leaflets, disposed within the lumen, and arranged to facilitate one-way upstream-to-downstream fluid flow through the lumen, the first axial level being upstream of the second axial level; and a flexible pouch that defines an interior space therein, the pouch shaped and coupled to the frame assembly such that: the pouch extends radially outward from the valve body, and the plurality of upstream arms and the plurality of downstream legs narrow the pouch therebetween to form a narrowed portion of the pouch, so as to define: an inner portion of the interior space, radially inward from the narrowed portion, and in fluid communication with the lumen, and an outer portion of the interior space, radially outward from the narrowed portion, and in fluid communication with the inner portion via the narrowed portion.
 2. The apparatus according to claim 1, wherein, at the narrowed portion, the plurality of downstream legs extend in an upstream direction past the plurality of upstream arms.
 3. The apparatus according to claim 1, wherein the plurality of upstream arms are disposed inside the pouch.
 4. The apparatus according to claim 1, wherein the plurality of upstream arms and the plurality of downstream legs are arranged such that, at the narrowed portion, the arms of the plurality of upstream arms and the legs of the plurality of downstream legs alternate circumferentially.
 5. The apparatus according to claim 1, wherein the inner portion of the interior space is in fluid communication with the lumen via a plurality of discrete windows defined by the apparatus.
 6. The apparatus according to claim 5, further comprising a belt wrapped around the frame assembly downstream of the windows, circumscribing the lumen, each of the windows being bounded, at a downstream edge of the window, by the belt.
 7. The apparatus according to claim 6, wherein the leaflets are arranged to form a plurality of commissures therebetween, and are attached to the frame assembly at the commissures, and wherein the belt is disposed over the commissures.
 8. The apparatus according to claim 1, wherein: the pouch has an upstream surface and a downstream surface, and, at the narrowed portion, each of the plurality of downstream legs pushes the downstream surface toward the upstream surface.
 9. The apparatus according to claim 8, wherein, at the narrowed portion, each of the plurality of downstream legs pushes the downstream surface into contact with the upstream surface.
 10. The apparatus according to claim 9, wherein, at the narrowed portion, each of the plurality of downstream legs forms a respective bulge in the upstream surface by pressing the downstream surface against the upstream surface.
 11. The apparatus according to claim 1, wherein the pouch is stitched to the plurality of upstream arms.
 12. The apparatus according to claim 11, wherein, at the narrowed portion, the pouch is stitched to the plurality of upstream arms but not to the plurality of downstream legs.
 13. The apparatus according to claim 1, wherein the frame assembly comprises (i) a valve frame that defines the valve body and the plurality of upstream arms, and (ii) an outer frame that circumscribes the valve frame, and defines the plurality of downstream legs.
 14. The apparatus according to claim 13, wherein an upstream portion of the pouch is attached to the valve frame, and a downstream portion of the pouch is attached to the outer frame.
 15. The apparatus according to claim 1, further comprising at least one coagulation component, disposed within the outer portion of the interior space, and configured to promote blood coagulation within the outer portion of the interior space.
 16. The apparatus according to claim 15, wherein the coagulation component is annular, and, within the outer portion of the interior space, circumscribes the longitudinal axis.
 17. Apparatus, comprising: a frame assembly that comprises: a valve body that circumscribes a longitudinal axis and defines a lumen along the axis; a plurality of upstream arms that are coupled to the valve body at a first axial level with respect to the longitudinal axis, each of the plurality of upstream arms extending radially outward from the valve body to a respective arm-tip; and a plurality of downstream legs that are coupled to the valve body at a second axial level with respect to the longitudinal axis, and that extend radially outward from the valve body and toward the plurality of upstream arms; a tubular liner that lines the lumen, and that has an upstream end and a downstream end; a plurality of prosthetic leaflets, disposed within the lumen, attached to the liner, and arranged to facilitate one-way upstream-to-downstream fluid flow through the lumen, the first axial level being upstream of the second axial level; a first sheet of flexible material, the first sheet having (i) a greater perimeter, and (ii) a smaller perimeter that defines an opening, the first sheet being attached to the plurality of upstream arms with the opening aligned with the lumen of the valve body; and a second sheet of flexible material: the second sheet having a first perimeter and a second perimeter, the first perimeter being attached to the greater perimeter of the first sheet around the greater perimeter of the first sheet, the second sheet extending from the first perimeter radially inwards and downstream toward the second perimeter, the second perimeter circumscribing, and attached to, the valve body at a third axial level that is downstream of the first axial level, wherein: the first sheet, the second sheet, and the liner define an inflatable pouch therebetween, the inflatable pouch defining an interior space therein, the first sheet defining an upstream wall of the pouch, the second sheet defining a radially-outer wall of the pouch, and the liner defining a radially-inner wall of the pouch, and each of the plurality of downstream legs presses the second sheet into contact with the first sheet.
 18. The apparatus according to claim 17, wherein the plurality of upstream arms are disposed inside the pouch.
 19. The apparatus according to claim 17, wherein each of the plurality of downstream legs forms a respective bulge in the first sheet by pressing the second sheet against the first sheet.
 20. The apparatus according to claim 17, wherein, the plurality of downstream legs extend in an upstream direction past the plurality of upstream arms.
 21. The apparatus according to claim 17, wherein the frame assembly comprises (i) a valve frame that defines the valve body and the plurality of upstream arms, and (ii) an outer frame that circumscribes the valve frame, and defines the plurality of downstream legs.
 22. The apparatus according to claim 21, wherein an upstream portion of the pouch is attached to the valve frame, and a downstream portion of the pouch is attached to the outer frame.
 23. The apparatus according to claim 17, wherein the plurality of downstream legs forms a narrowed portion of the pouch by pressing the second sheet into contact with the first sheet, the narrowed portion of the pouch circumscribing the valve body.
 24. The apparatus according to claim 23, wherein, at the narrowed portion, the second sheet is not stitched to the plurality of downstream legs.
 25. The apparatus according to claim 23, wherein the plurality of upstream arms and the plurality of downstream legs are arranged such that, at the narrowed portion, the arms of the plurality of upstream arms and the legs of the plurality of downstream legs alternate circumferentially.
 26. The apparatus according to claim 23, wherein the narrowed portion of the pouch shapes the pouch to define: an inner portion of the interior space, radially inward from the narrowed portion, and in fluid communication with the lumen, and an outer portion of the interior space, radially outward from the narrowed portion, and in fluid communication with the inner portion via the narrowed portion.
 27. The apparatus according to claim 26, further comprising at least one coagulation component, disposed within the outer portion of the interior space, and configured to promote blood coagulation within the outer portion of the interior space.
 28. The apparatus according to claim 27, wherein the coagulation component is annular, and, within the outer portion of the interior space, circumscribes the longitudinal axis.
 29. The apparatus according to claim 17, wherein the interior space is in fluid communication with the lumen via a plurality of discrete windows defined by the apparatus.
 30. The apparatus according to claim 29, further comprising a belt wrapped around the frame assembly downstream of the windows, circumscribing the lumen, each of the windows being bounded, at a downstream edge of the window, by the belt.
 31. The apparatus according to claim 30, wherein the leaflets are arranged to form a plurality of commissures therebetween, and are attached to the frame assembly at the commissures, and wherein the belt is disposed over the commissures. 